ToGrooveshark is pretty simple to use. Just log in using your Grooveshark credentials, then open up Spotify and select all the songs in a playlist. Right-click on that group of songs, click "Copy HTTP Link" and paste it in the ToGrooveshark box. It'll search for equivalents of those songs on Grooveshark and create a playlist for you. It's not as automated a process as we'd like, but it works pretty well (though it may miss a few if their track names don't quite match up). Hit the link to check it out.